Ironic have updated some parameters to have a consistent name
across drivers. This patch is updating devstack to stop using the
pxe_deploy_{kernel, ramdisk} parameters which have been deprecated since
early Kilo eliminating the deprecation warnings in the logs.
WARNING ironic.drivers.modules.pxe [-] The "pxe_deploy_kernel" parameter
is deprecated. Please update the node 267e42c8-df07-49f5-bc7f-48b566acb109
to use "deploy_kernel" instead.
WARNING ironic.drivers.modules.pxe [-] The "pxe_deploy_ramdisk" parameter
is deprecated. Please update the node 267e42c8-df07-49f5-bc7f-48b566acb109
to use "deploy_ramdisk" instead.
Change-Id: I3dcf8df130efc0c2ea35695018bedba31bf0570c